The present invention relates to a measuring device for determination of a rotary angle. In particular, it relates to a device for contactless determination of a rotary angle by means of sensor coils arranged on a coil body and having values which are changeable in dependence upon regions of a measuring part associated with the sensor coils.
Devices of the above mentioned general type are known in the art. Such devices are disclosed for example in the German document DE-OS 40 01 544.0. The devices disclosed in this reference include a coil body composed of two cores which have an approximately semicrescent shaped cross-section and are offset relative to one another in an axial direction. The cores are also offset relative to one another in a radial direction by 180 degrees so that both flat surfaces of the cores face one another. A coil is wound on each core in a peripheral direction and is in an operative connection with a measuring part composed of electrically conducting and/or ferromagnetic material. The winding of the coil over the whole periphery of the core forms a region which faces the measuring part, and a coil region located on the lower side of the measuring core. The coil region arranged on the lower side is excluded from the measuring value determination or in other words it reduces the useable part of the inductivity change. Thereby the measuring sensitivity of the measuring device is reduced. Furthermore, only the region which faces the coil is available for producing the measuring signal. Also, the coils arranged on the individual cores have a relatively high temperature drift.
The German document DE-PS 38 15 074 discloses a measuring device in which several coils are arranged on the inner side of the sleeve and are in operative connection with a measuring part movable in the sleeve. No wire coils can be wound on the inner side of this sleeve. The measuring region with the use of a throttle valve transmitter must be more than 100 degrees. This cannot be obtained with an arrangement of four coils.